Mardi 26 mars à 11h00, salle des séminaires IRPHE
Abstract: Understanding the dynamics of flame propagation is crucial for fire safety research. This seminar presents the unstable behaviors of flame spread along solid combustibles and lean premixed hydrogen in Hele-Shaw cells. First, experimental observations of the flame spread in concurrent oxidizer flow are presented. A thin disk-shaped paper is ignited at the center, and subsequent flame spread behaviors are observed. At high flow rates, a continuous circular flame spreads outwardly, while the flame breaks up at lower flow rates due to thermal-diffusive instability. The latter exhibits two apparently different behaviors: random motion and spiral motion. Image analysis quantifies these behaviors, and their physical distinctions are discussed.
Second, the dynamics of hydrogen flame in a Hele-Shaw cell are investigated through numerical simulations. The flame front undergoes hydrodynamic and thermal diffusive instabilities, and the number and spacing of cusps are evaluated. Comparison between maximum and critical wavelengths from dispersion relations and simulation results provides insights into the dominant factors driving the dynamics. This comprehensive study on flame spread and hydrogen combustion in Hele-Shaw cells, contributing valuable knowledge to fire safety research.
Tsuneyoshi Matsuoka / Toyohashi University of Technology, Japan